Urinary liver-type fatty acid-binding protein level as a predictive biomarker of contrast-induced acute kidney injury

Eur J Clin Invest 2012; 42 (5): 557–563 Background Contrast‐induced acute kidney injury (CI‐AKI) is a well‐known complication of contrast medium exposure in patients with chronic kidney disease. However, there are no biological markers to accurately predict the onset of CI‐AKI. Liver‐type fatty acid‐binding protein (L‐FABP), an intracellular carrier protein for free fatty acids, is markedly upregulated and abundantly expressed in the proximal tubules after renal ischaemia. We prospectively investigated whether urinary L‐FABP is a suitable marker for the prediction of CI‐AKI. Methods We performed a prospective study of 220 consecutive patients with chronic kidney disease who underwent elective catheterization [serum creatinine (Cr) ≥ 1·2 mg/dL (106 M)]. Serum Cr and L‐FABP levels were measured immediately before and 1 and 2 days after the procedure. CI‐AKI was defined as an increase in serum Cr level of ≥ 0·3 mg/dL within 48 h after the procedure. Results We observed the development of CI‐AKI in 19 patients (8·6%). Urinary L‐FABP levels were significantly higher in patients with CI‐AKI than those without CI‐AKI before contrast medium exposure. Receiver operating characteristic analysis showed that baseline urinary L‐FABP level exhibited 82% sensitivity and 69% specificity, at a cut‐off value of 24·5 μg/g Cr. Using multivariate analysis, we found that independent predictors of CI‐AKI development were L‐FABP level of ≥ 24·5 μg/g Cr [odds ratio (OR): 9·10; 95% confidence interval (CI), 3·20–28·9], and left ventricular ejection fraction ≤ 40% (OR, 3·42; 95% CI, 1·07–10·8). Conclusions Urinary L‐FABP level is useful for predicting the onset of CI‐AKI before contrast medium exposure.